3 files changed, 23 insertions, 2 deletions
diff --git a/src/nix-channel/nix-channel.cc b/src/nix-channel/nix-channel.cc
index 3ccf620c9..e48f7af9a 100755
--- a/src/nix-channel/nix-channel.cc
+++ b/src/nix-channel/nix-channel.cc
@@ -76,6 +76,13 @@ static void update(const StringSet & channelNames)
 
     auto store = openStore();
 
+    auto [fd, unpackChannelPath] = createTempFile();
+    writeFull(fd.get(),
+        #include "unpack-channel.nix.gen.hh"
+        );
+    fd = -1;
+    AutoDelete del(unpackChannelPath, false);
+
     // Download each channel.
     Strings exprs;
     for (const auto & channel : channels) {
@@ -104,7 +111,7 @@ static void update(const StringSet & channelNames)
 
         bool unpacked = false;
         if (std::regex_search(filename, std::regex("\\.tar\\.(gz|bz2|xz)$"))) {
-            runProgram(settings.nixBinDir + "/nix-build", false, { "--no-out-link", "--expr", "import <nix/unpack-channel.nix> "
+            runProgram(settings.nixBinDir + "/nix-build", false, { "--no-out-link", "--expr", "import " + unpackChannelPath +
                         "{ name = \"" + cname + "\"; channelName = \"" + name + "\"; src = builtins.storePath \"" + filename + "\"; }" });
             unpacked = true;
         }
@@ -125,7 +132,7 @@ static void update(const StringSet & channelNames)
     // Unpack the channel tarballs into the Nix store and install them
     // into the channels profile.
     std::cerr << "unpacking channels...\n";
-    Strings envArgs{ "--profile", profile, "--file", "<nix/unpack-channel.nix>", "--install", "--from-expression" };
+    Strings envArgs{ "--profile", profile, "--file", unpackChannelPath, "--install", "--from-expression" };
     for (auto & expr : exprs)
         envArgs.push_back(std::move(expr));
     envArgs.push_back("--quiet");
diff --git a/src/nix-channel/unpack-channel.nix b/src/nix-channel/unpack-channel.nix
new file mode 100644
index 000000000..10515bc8b
--- /dev/null
+++ b/src/nix-channel/unpack-channel.nix
@@ -0,0 +1,12 @@
+{ name, channelName, src }:
+
+derivation {
+  builder = "builtin:unpack-channel";
+
+  system = "builtin";
+
+  inherit name channelName src;
+
+  # No point in doing this remotely.
+  preferLocalBuild = true;
+}
diff --git a/src/nix/local.mk b/src/nix/local.mk
index e96200685..ab4e9121b 100644
--- a/src/nix/local.mk
+++ b/src/nix/local.mk
@@ -29,3 +29,5 @@ $(eval $(call install-symlink, $(bindir)/nix, $(libexecdir)/nix/build-remote))
 src/nix-env/user-env.cc: src/nix-env/buildenv.nix.gen.hh
 
 src/nix/develop.cc: src/nix/get-env.sh.gen.hh
+
+src/nix-channel/nix-channel.cc: src/nix-channel/unpack-channel.nix.gen.hh